Musnad Ahmad 27:161

Isma'il narrated to us, Ibn 'Awn narrated to us, from Nafi', from Ibn 'Umar, who said: 'Umar acquired land in Khaybar, so he came to the Prophet, peace and blessings of Allah be upon him, and sought his counsel regarding it. He said: "I have acquired land in Khaybar, and I have never acquired property more precious to me than it, so what do you command me to do with it?" He said: "If you wish, you may withhold its principal and give its produce as charity." He said: So 'Umar gave it as charity, [stipulating] that it shall not be sold, nor given away, nor inherited. He said: So 'Umar gave it as charity to the poor, the relatives, the freeing of slaves, in the way of Allah, the traveler, and the guest. There is no blame upon the one who manages it if he eats from it in a reasonable manner, or feeds a friend, without accumulating wealth from it.